Preparation

Make filling:
Chop 1/2 cup fennel fronds and reserve, then remove stalks and tough outer layer from bulb. Halve bulb and grate on large holes of a 4-sided grater.

Heat 1/3 cup olive oil in a 12-inch heavy skillet over high heat until hot but not smoking and sauté onion, stirring, until softened, 2 to 3 minutes. Add pumpkin and grated fennel and cook, stirring frequently and scraping up any brown bits, until vegetables are soft, about 12 minutes. Stir in bulgur and chile flakes and cook 2 minutes. Add fennel fronds and mint, then remove from heat and cover. Let stand 15 minutes. Stir in cheeses and season with salt and black pepper.

Make pastries:
Keeping remaining sheets covered, brush 1 spring-roll sheet lightly with some safflower oil and place a scant 2 tablespoons filling 1 inch from edge closest to you. Form filling into a log, leaving a 1/2-inch border on each side. Fold bottom of sheet over filling, then fold in sides. Loosely roll away from you to form a cylinder, brush top edge with egg white, and press to seal. Bend cylinder into a horseshoe shape. Make more pastries in same manner.

Heat enough safflower and olive oils to measure 3/4 inch in a deep 12-inch heavy skillet over moderately high heat until a deep-fat thermometer registers 350°F. Fry pastries 2 or 3 at a time, turning once, until golden brown, 3 to 4 minutes.

Transfer with a slotted spoon to paper towels to drain and return oils to 350°F between batches. Serve warm or at room temperature.

Cooks' note:
·Filling can be made 1 day ahead. Let cool, and chill, covered. Return to room temperature before using.